40_weeks_equals_10_months.py

from dateutil.relativedelta import relativedelta
from datetime import datetime, timedelta

first_date = datetime(1970, 1, 1)
date_list = [first_date + timedelta(days=x) for x in xrange(0, 1000000)]
forty_weeks = 40 * 7

for date in date_list:
    if ((date + relativedelta(months=10)) - date).days == forty_weeks:
        print('40 weeks equals 10 months! Starting at {}'.format(date))
        break
else:
    print('Not so lucky =(')